使用PowerShell脚本递增DevOps变量组值时遇TF400898错误

在使用PowerShell脚本获取、递增并更新Azure DevOps变量组中变量值时，触发TF400898内部错误，推测是递增后的值$versionNumber写入JSON字符串的方式错误导致的。

脚本代码：

# Base64-encodes the Personal Access Token (PAT) appropriately
$base64AuthInfo = [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(("{0}:{1}" -f "","$env:SYSTEM_ACCESSTOKEN")))
$url = "$($env:SYSTEM_TEAMFOUNDATIONCOLLECTIONURI)$env:SYSTEM_TEAMPROJECTID/_apis/distributedtask/variablegroups/1?api-version=6.0-preview.1"

$pipeline = Invoke-RestMethod -Uri $url -Method Get -ContentType "application/json" -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)}
Write-Host "Get Variable Value:" $pipeline.variables.MinorVersion.value

$versionNumber = [int]$pipeline.variables.MinorVersion.value
$versionNumber++
Write-Host "$versionNumber Variable Value:" $versionNumber

$json = '{"id":2555,"type":"Vsts","name":"VersionNumberVG","variables":{"MinorVersion":{"value":$versionNumber}}}'
$pipeline = Invoke-RestMethod -Uri $url -Method Put -Body $json -ContentType "application/json" -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)}
Write-Host "PUT New Variable Value:" $pipeline.variables.MinorVersion.value

$pipeline = Invoke-RestMethod -Uri $url -Method Get -ContentType "application/json" -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)}
Write-Host "Get Variable Value:" $pipeline.variables.MinorVersion.value

错误信息：

Invoke-RestMethod : {"$id":"1","innerException":null,"message":"TF400898: An Internal Error Occurred. Activity Id: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxx.","typeName":"Newtonsoft.Json.JsonReaderException, Newtonsoft.Json","typeKey":"JsonReaderException","errorCode":0,"eventId":0}
At line:13 char:13
+ $pipeline = Invoke-RestMethod -Uri $url -Method Put -Body $json -Cont ...
+             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (System.Net.HttpWebRequest:HttpWebRequest) [Invoke-RestMethod], WebException
    + FullyQualifiedErrorId : WebCmdletWebResponseException,Microsoft.PowerShell.Commands.InvokeRestMethodCommand

核心问题是单引号包裹的字符串中PowerShell不会解析变量，导致发送的JSON里是$versionNumber字符串而非实际数值，触发JSON解析错误。以下是两种修复方式：

方法1：双引号拼接并转义内部引号 #

将JSON字符串改为双引号包裹，同时对内部的双引号用反引号`转义，让PowerShell正确解析变量：

$json = "{`"id`":2555,`"type`":`"Vsts`",`"name`":`"VersionNumberVG`",`"variables`":{`"MinorVersion`":{`"value`":$versionNumber}}}"

方法2：构建PS对象再转JSON（推荐） #

手动拼接JSON容易出错，更可靠的方式是先创建PowerShell自定义对象，再用ConvertTo-Json生成标准JSON：

$variableGroup = [PSCustomObject]@{
    id = 2555
    type = "Vsts"
    name = "VersionNumberVG"
    variables = [PSCustomObject]@{
        MinorVersion = [PSCustomObject]@{
            value = $versionNumber
        }
    }
}
$json = $variableGroup | ConvertTo-Json -Depth 3

额外注意事项 #

• 确保JSON中的id字段和URL里的变量组ID一致（你的URL中是1，但JSON写的2555，需检查匹配）
• 使用ConvertTo-Json时要指定足够的-Depth参数，避免嵌套对象被截断

修改后的完整脚本 #

# Base64-encodes the Personal Access Token (PAT) appropriately
$base64AuthInfo = [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(("{0}:{1}" -f "","$env:SYSTEM_ACCESSTOKEN")))
$url = "$($env:SYSTEM_TEAMFOUNDATIONCOLLECTIONURI)$env:SYSTEM_TEAMPROJECTID/_apis/distributedtask/variablegroups/1?api-version=6.0-preview.1"

$pipeline = Invoke-RestMethod -Uri $url -Method Get -ContentType "application/json" -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)}
Write-Host "Get Variable Value:" $pipeline.variables.MinorVersion.value

$versionNumber = [int]$pipeline.variables.MinorVersion.value
$versionNumber++
Write-Host "Updated Variable Value:" $versionNumber

# 构建对象并转换为标准JSON
$variableGroup = [PSCustomObject]@{
    id = 1  # 与URL中的变量组ID保持一致
    type = "Vsts"
    name = "VersionNumberVG"
    variables = [PSCustomObject]@{
        MinorVersion = [PSCustomObject]@{
            value = $versionNumber
        }
    }
}
$json = $variableGroup | ConvertTo-Json -Depth 3

$pipeline = Invoke-RestMethod -Uri $url -Method Put -Body $json -ContentType "application/json" -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)}
Write-Host "PUT New Variable Value:" $pipeline.variables.MinorVersion.value

$pipeline = Invoke-RestMethod -Uri $url -Method Get -ContentType "application/json" -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)}
Write-Host "Get Variable Value:" $pipeline.variables.MinorVersion.value

内容的提问来源于stack exchange，提问作者CompileNow